зеркало из https://github.com/mozilla/gecko-dev.git
112 строки
3.8 KiB
C++
112 строки
3.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsTLiteralString_h
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#define nsTLiteralString_h
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#include "nsTStringRepr.h"
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/**
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* nsTLiteralString_CharT
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*
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* Stores a null-terminated, immutable sequence of characters.
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*
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* nsTString-lookalike that restricts its string value to a literal character
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* sequence. Can be implicitly cast to const nsTString& (the const is
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* essential, since this class's data are not writable). The data are assumed
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* to be static (permanent) and therefore, as an optimization, this class
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* does not have a destructor.
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*/
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template <typename T>
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class nsTLiteralString : public mozilla::detail::nsTStringRepr<T> {
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public:
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typedef nsTLiteralString<T> self_type;
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#ifdef __clang__
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// bindgen w/ clang 3.9 at least chokes on a typedef, but using is okay.
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using typename mozilla::detail::nsTStringRepr<T>::base_string_type;
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#else
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// On the other hand msvc chokes on the using statement. It seems others
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// don't care either way so we lump them in here.
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typedef typename mozilla::detail::nsTStringRepr<T>::base_string_type
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base_string_type;
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#endif
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typedef typename base_string_type::char_type char_type;
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typedef typename base_string_type::size_type size_type;
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typedef typename base_string_type::DataFlags DataFlags;
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typedef typename base_string_type::ClassFlags ClassFlags;
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public:
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/**
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* constructor
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*/
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template <size_type N>
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explicit constexpr nsTLiteralString(const char_type (&aStr)[N])
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: nsTLiteralString(aStr, N - 1) {}
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/**
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* For compatibility with existing code that requires const ns[C]String*.
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* Use sparingly. If possible, rewrite code to use const ns[C]String&
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* and the implicit cast will just work.
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*/
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MOZ_LIFETIME_BOUND const nsTString<T>& AsString() const {
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return *reinterpret_cast<const nsTString<T>*>(this);
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}
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MOZ_LIFETIME_BOUND operator const nsTString<T>&() const { return AsString(); }
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template <typename N, typename Dummy>
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struct raw_type {
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typedef N* type;
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};
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#ifdef MOZ_USE_CHAR16_WRAPPER
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template <typename Dummy>
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struct raw_type<char16_t, Dummy> {
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typedef char16ptr_t type;
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};
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#endif
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/**
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* Prohibit get() on temporaries as in "x"_ns.get().
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* These should be written as just "x", using a string literal directly.
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*/
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const typename raw_type<T, int>::type get() const&& = delete;
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const typename raw_type<T, int>::type get() const& { return this->mData; }
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// At least older gcc versions do not accept these friend declarations,
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// complaining about an "invalid argument list" here, but not where the actual
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// operators are defined or used. We make the supposed-to-be-private constructor
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// public when building with gcc, relying on the default clang builds to fail if
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// any non-private use of that constructor would get into the codebase.
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#if defined(__clang__)
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private:
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friend constexpr auto operator"" _ns(const char* aStr, std::size_t aLen);
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friend constexpr auto operator"" _ns(const char16_t* aStr, std::size_t aLen);
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#else
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public:
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#endif
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// Only for use by operator""
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constexpr nsTLiteralString(const char_type* aStr, size_t aLen)
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: base_string_type(const_cast<char_type*>(aStr), aLen,
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DataFlags::TERMINATED | DataFlags::LITERAL,
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ClassFlags::NULL_TERMINATED) {}
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public:
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// NOT TO BE IMPLEMENTED
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template <size_type N>
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nsTLiteralString(char_type (&aStr)[N]) = delete;
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self_type& operator=(const self_type&) = delete;
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};
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extern template class nsTLiteralString<char>;
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extern template class nsTLiteralString<char16_t>;
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#endif
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